Abstract:
Subways generate large pressure forces in subway tunnels while traveling. This wind energy can be harvested for power. The MACE (Mass Airflow Collection Equipment) turbine is an existing system that can be utilized to collect this wind energy. In initial testing done by WWT Tunnel, LLC, a ten foot turbine unit generated around 77.7 kWh, when the air reached a peak speed of 56.7 mph (25.35 m/s), in a total time of two and a half minutes. This turbine will likely be produced by several companies with their own variations, so the design for this turbine is not identical, however it is similar. That turbine is optimized here for maximum power output by analyzing the wake effect between turbines and the optimal placement and spacing along the length of a subway tunnel. One model is examined and then tested different placement configurations along the tunnel to minimize wake effect and optimize power output. This is done by modeling a turbine in SolidWorks and then using computational fluid dynamics modeling in ANSYS Fluent to simulate the airflow of the train passing. Washington Metro is an average subway station and this was used for the wind speed data so the configuration would be comparable for all subway stations. This research analyzes how turbines could be placed in a tunnel and in what configuration for maximum power output, by minimizing the wake effect. Simulation results indicate that a circular pattern works well for the turbines where the end of one is in line with the head of another, but placed 120 degrees clockwise along the wall. This produced only a slight reduction in wind speed between the turbines, on average 1-3 m/s (2-6 mph) difference. Further research should be conducted on more patterns of turbine placement and how the positioning would need to vary with increased wind speeds.
